Refrigerating apparatus including means for cooling compressor motor



Nov. 23, 1965 A. W. MCCLURE 3,218,825 REFRIGERATING APPARATUS INCLUDINGMEANS FOR COOLING COMPRESSOR MOTOR Filed Aug. 14, 1962 ATTORNEYS Nov.23, 1965 A. w. MGCLURE 3,218,825

REFRIGERATING APPARATUS INCLUDING MEANS FOR COOLING COMPRES SOR MOTOR 2Sheets-Sheet 2 Filed Aug. 14, 1962 INVENTOR.

ARTHUR W. MC CLURE BY MIM] MV ATTORNEYS United States Patent O 3,218,825REFRIGERATING APPARATUS INCLUD- ING MEANS FOR COOLING COMPRES- SOR MOTORArthur W. McClure, La Crosse, Wis., assigner to The Trane Company, LaCrosse, Wis., a corporation of Wisconsin Filed Aug. 14, 1962, Ser. No.216,842 3 Claims. (Cl. 62-505) This invention relates to refrigeratingapparatus of the type including a motor-compressor assembly, andparticularly to apparatus in which the motor and compressor are housedin a sealed unit.

It is an object of this invention to provide improved means for coolingthe motor of refrigerating apparatus using the liquid refrigerant of therefrigerating apparatus as a heat exchange medium.

It is another object of this invention to conduct liquid refrigerantthrough passageways of the motor stator to cool the motor stator byevaporation of refrigerant and to provide means for conducting thevaporized refrigerant to the condenser or to the evaporator.

It is another object of the invention to provide means for conductingliquid refrigerant from the condenser to the evaporator only when themotor has a predetermined supply of refrigerant liquid for cooling.

Other objects and advantages of the invention will appear as thespecification proceeds to describe the invention with reference to theaccompanying drawings in which:

FIGURE 1 is a partly diagrammatic view in elevation of the refrigeratingapparatus with portions sectioned to more clearly show the interiorconstruction;

FIGURE 2 is a cross-sectional view taken on line 2-2 of FIGURE l;

FIGURE 3 is an enlarged sectional view taken on an axial plane throughone of the stator supporting bars and showing a portion of the interiorof the motor; and

FIGURE 4 is a partly diagrammatic view in elevation of a modification ofthe refrigerating apparatus with portions sectioned to more clearly showthe interior construction.

Referring now to FIGURE 1, an electric motor has at one end a firststage compressor 12 and at the other end a second stage compressor 14. Across-over pipe 16 conducts gas from the discharge of the first stage 12to the inlet of the second stage 14.

The gas discharged from the second stage 14 flows through a pipe 18 to acondenser 20. The condenser 20 may be of the shell-and-tube type inwhich cooling water flows through the tubing 22 and the refrigerant isin the shell outside the tubes. Refrigerant liquid condensed incondenser 20 flows by gravity through pipe 23 to a reservoir 24. Aconduit 25 is in fluid flow communication with the bottom of reservoir24 and conducts liquid refrigerant to the motor 10.

A conduit 26 is connected to the reservoir 24 at a point above itsbottom to conduct overflow liquid refrigerant when the liquid rises tolevel 27. A properly sized oat valve 28 maintains a liquid Ievel in thechamber of the valve. Conduit 29 conducts the liquid and flash gas toevaporator 30 which is also of the shell-and-tube type in which thesecondary refrigerant liquid such as water or brine flows through thetubing 31 and the refrigerant is in the shell outside the tubing.

The secondary refrigerant liquid circulates between the evaporator 30and the cooling load served by the refrigeration apparatus to transferheat from the load to the evaporator 30. In removing heat from thesecondary refrigerant, the refrigerant in the evaporator 30` boilsforming vapor which passes through the liquid eliminator 3,218,825Patented Nov. 23, 1965 ICC 32 and thence into the suction pipe 34 of theevaporator 30 to the inlet of the first stage compressor 12.

The motor 10 has a fluid tight casing 36 secured in fluid sealingrelationship to the housings of compressors 12 and 14. Bars 37 aresecured to the casing 36 and to a motor stator 38 to support the motorstator 38 in the casing 36. As more clearly shown in FIGURE 3, thestator 38 comprises large diameter laminations 43 and smaller diameterlaminations 44 thus providing annular spaces 45 between the stator 38and the casing 36 for the flow of refrigerant. The refrigerant flowingin annular spaces 45 contacts and cools large surface areas of thestator 38, the bars 37, and the casing 36. Rings 40 and 41 are securedto the casing 36 to provide additional support for the stator 38 andbars 37, and to seal the annular spaces 45 from the interior of themotor. A manifold 46 collects the vaporized refrigerant for flow intoconduit 47 and thence to condensor 20.

A shaft 48 is rotatably supported in the casing 36 by bearings (notshown) and extends at one end into compressor 12 and has a centrifugalimpeller 52 secured thereto. The other end of shaft 48 extends intocornpressor 14 and has a centrifugal impeller 54 secured thereto. Amotor rotor 56 is secured to the shaft 48 and has fan blades 58 forcirculating the refrigerant vapor over the surfaces of the shaft 48, therotor 56, the stator 38, and the ends of the stator windings 59. Thiscirculation of refrigerant vapor transfers heat from these parts to thecooled parts of the motor. The spaces surrounding the rotor 56 and thespaces surrounding the end turns of the windings 59 are filled withrefrigerant vapor because of the pressures and temperatures existing inthese spaces.

Under certain temperature conditions which might occur after a shut downof the apparatus, there can be little or no liquid refrigerant in thecasing 36, the conduit 25, and the reservoir 24. When the apparatus isstarted under such conditions, the refrigerant condensate first producedby condenser 20 flows directly through conduit 25 to the motor casing 36for motor cooling. Refrigerant liquid does not flow through conduit 26to the evaporator 30 until the liquid in reservoir 24 rises to the level27 which is opposite the bottom of the entrance to conduit 26.

With the liquid refrigerant at level 27 in the reservoir 24, the stator38 is substantially submerged in liquid, because the liquid level in theannular passageways 45 is also substantially at level 27. With thisarrangement, substantially all of the outer surfare area of laminations43 and 44 and substantially all of the surface areas of laminations 43defining annular spaces 45 are wetted with liquid refrigerant. Veryeffective cooling of the stator is therefore obtained.

Referring now to FIGURE 4 which shows a modification of the apparatus ofFIGURE l and in which corresponding parts have like numerals, therefrigerant liquid flows from condenser 20 through conduit 60 to a floatvalve 62 which maintains a liquid level in the chamber of the valve.Conduit 64 conducts liquid refrigerant to the motor casing 36. A valve66 is positioned in the conduit 64 to control the flow therethrough.

A conduit 68 conducts vaporized refrigerant from the manifold 46 of themotor casing 36 to the evaporator 30 at a point below the eliminator 32.

A conduit 70 receives refrigerant liquid which overflows from conduit 64and conducts such refrigerant liquid to evaporator 30.

The operation of the apparatus of FIGURE 4 is similar to that of FIGURE1 in that on initiating operation the refrigerant liquid first producedby the condenser 20 flows directly through conduit 64 to the motorcasing 36 for motor cooling.

Refrigerant liquid does not flow through conduit 70 until liquid inconduit 64 rises to the outlet to conduit 70. At this condition, theliquid refrigerant in the casing 36 is substantially at the same levelas the liquid refrigerant in conduit 70 and the desired effective motorcooling is obtained as explained more fully with reference to FIGURE l.

Although a two-stage compressor has been shown, it should be understoodthat the apparatus is also applicable to an apparatus in which the motordrives a single stage compressor.

While I have described the foregoing preferred embodiment of myinvention, I contemplate that many changes may be made without departingfrom the scope or spirit of my invention and I desire to be limited onlyby the claims.

I claim:

1. In refrigerating apparatus, the combination of an evaporator forvaporizing refrigerant, a condenser for liquefying refrigerant, acompressor for circulating refrigerant through said condenser andevaporator, a casing, an electric motor stator mounted in said casingand having grooves in its periphery, means providing an annular spacebetween said electric motor stator and said casing, means for conductingrefrigerant liquid from said condenser to the annular space between saidelectric motor stator and said casing to cool said electric motor statorand said casing, means for conducting refrigerant vapor from saidcasing, a rotor and shaft assembly rotatably mounted in said casing, fanmeans mounted on said rotor and shaft assembly for circulatingrefrigerant vapor over the surfaces of said shaft and rotor assembly,said stator and said casing to transfer heat from said shaft and rotorassembly and said stator to said casing, and means for additionallyconducting refrigerant liquid from said condenser to said evaporatorwhen the level of refrigerant liquid in said casing exceeds apredetermined point.

2. In refrigerating apparatus, the combination of an evaporator forvaporizing refrigerant, a condenser for liquefying refrigerant, acompressor for circulating refrigerant through said condenser andevaporator, a casing, an electric motor stator mounted in said casingand having grooves in its periphery, means providing an annular spacebetween said electric motor stator and said casing, means for conductingrefrigerant liquid from said condenser to the annular space between saidelectric r ROBERT A.

motor stator and said casing to cool said electric motor stator and saidcasing, means for conducting refrigerant vapor from the annular space tosaid condenser, a rotor and shaft assembly rotatably mounted in saidcasing, fan means mounted on said rotor and shaft assembly forcirculating refrigerant vapor over the surfaces of said shaft and rotorassembly, said stator and said casing to transfer heat from said shaftand rotor assembly and said stator to said casing, and means foradditionally conducting refrigerant liquid from said condenser to saidevaporator when the level of refrigerant liquid in said casing exceeds apredetermined point.

3. In refrigerating apparatus, the combination of an evaporator forvaporizing refrigerant, a condenser for liquefying refrigerant, acompressor for circulating refrigerant through said condenser andevaporator, a casing, an electric motor stator mounted in said casingand having grooves in its periphery, means providing an annular spacebetween said electric motor stator and said casing, means for conductingrefrigerant liquid from said condenser to the annular space between saidelectric motor stator and said casing to cool said electric motor statorand said casing, means for conducting refrigerant vapor from the annularspace to said evaporator, a rotor and shaft assembly rotatably mountedin said casing, fan means mounted on said rotor and shaft assembly forcirculating refrigerant vapor over the surfaces of said shaft and rotorassembly, said stator and said casing to transfer heat from said shaftand rotor assembly and said stator to said casing, and means foradditionally conducting refrigerant liquid from said condenser to saidevaporator when the level of refrigerant liquid in said casing exceeds apredetermined point.

References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS3/ 1942 Germany. 3/1961 Great Britain.

OLEARY, Primary Examiner.

MEYER PERLIN, Examiner.

1. IN REFRIGERATING APPARATUS, THE COMBINATION OF AN EVAPORATOR FORVAPORIZING REFRIGERANT, A CONDENSER FOR LIQUEFYING REFRIGERANT, ACOMPRESSOR FOR CIRCULATING REFRIGERANT THROUGH SAID CONDENSER ANDEVAPORATOR, A CASING, AN ELECTRIC MOTOR STATOR MOUNTED IN SAID CASINGAND HAVING GROOVES IN ITS PERIPHERY, MEANS PROVIDING AN ANNULAR SPACEBETWEEN SAID ELECTRIC MOTOR STATOR AND SAID CASING, MEANS FOR CONDUCTINGREFRIGERANT LIQUID FROM SAID CONDENSER TO THE ANNULAR SPACE BETWEEN SAIDELECTRIC MOTOR STATOR AND SAID CASING TO COOL SAID ELECTRIC MOTOR STATORAND SAID CASING, MEANS FOR CONDUCTING REFRIGERANT VAPOR FROM SAIDCASING, A ROTOR AND SHAFT ASSEMBLY ROTATABLY MOUNTED IN SAID CASING, FANMEANS MOUNTED ON SAID ROTOR AND SHAFT ASSEMBLY FOR CIRCULATINGREFRIGERANT VAPOR OVER THE SURFACES OF SAID SHAFT AND ROTOR ASSEMBLY,SAID STATOR AND SAID CASING TO TRANSFER HEAT FROM SAID SHAFT AND ROTORASSEMBLY AND SAID STATOR TO SAID CASING, AND MEANS FOR ADDITIONALLYCONDUCTING REFRIGERANT LIQUID FROM SAID CONDENSER TO SAID EVAPORATORWHEN THE LEVEL OF REFRIGERANT LIQUID IN SAID CASING EXCEEDS APREDETERMINED POINT.